Automatic weighing apparatus



PATENTED JAN. 5, 1904.

W. NORTHROP.

AUTOMATIC WEIGHING APPARATUS;

APPLICATION FILED NOV. '1, 1902.

NO MODEL.

UNITED STATES Patented January 5, 1904.

PATENT OEEIcE.

WALTER NORTHROP, OF TORONTO, CANADA, ASSIGNOR TO HOVVSON & HOWSON, TRUSTEES, OF PHILADELPHIA, PENNSYLVANIA.

AUTOMATIC WEIGHING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 748,644, dated January 5, 1904.

Application filed November 4, 1902. erm-l No. 130,088. (No model.)

To all whom it may concern.-

Be it known that I, WALTER Nonrnnor, of the city of Toronto, county of York, Province of Ontario, Canada, have invented certain new and useful Improvements in Automatic Weighing Apparatus, of which the following is a specification.

My invention relates particularly to scales working in conjunction with a delivery-spout provided with automatic cut-off apparatus controlled by the movement of the scale-beam; and my object is to devise means for weighing comparatively light granular materials in small parcels with great accuracy.

In my scale I employ a main-stream cut-off in such a manner as to be progressively reduced in flow by the falling of the scale-beam. To make the tapering of the stream more certain and efiective, I arrange the apparatus so that the first movement of the scale-beam is made with less than the full weight on the weight-pan and the final movement to the position of balance against the full weight, so that the flow is reduced very rapidly at first and then slowly tapered 011 till the exact amount required has been discharged.

Figure 1 is a perspective view of my improved apparatus. Fig. 2 is a rear sectional elevation of a portion of the apparatus. Fig. 3 is a plan view of the same parts. Figs. 4.- and 5 show in plan views various modifications of the discharge-opening in the deliveryspout.

In the drawings like letters of reference indicate corresponding parts in the different figures.

In Fig. l, A is the supporting-stand of the apparatus, the exact shape of which is of course immaterial. This stand supports a suitably-hung scale-beam B, provided with the weight-pan G and the scale-pan D. .Above the scale-pan and connected with the same hangers a is the receiving-box E, located below the lower end of the discharge-spout F, secured to the frame of the machine. The receiving-box has two doors G, hinged at Z) and adapted to close its open bottom. A weighted arm H extends outwardly from each of these doors, thus normally maintaining them closed, as shown in Fig. 1. Fixed arms I extend out from the frame of the machine below the weighted arms H.

Supposing a weighed portion of material to have been discharged into the receivingbox, it maybe emptied into a package placed on the scale-pan by pressing down the latter to cause the weighted arms II to be brought into contact with the arms I, thus rocking them and opening the doors. (See Fig. 2.)

The discharge-spout F has a slanting false bottom formed near its upper end, forming a hopper provided with a discharge-opening c. This opening, as will be seen on reference to Fig. 3, is taperedthat is to say, its sides are not parallel to one another.

Below the discharge-opening I journal a spindle J in the sides of the discharge-spout. Arms d extend up from this spindle and carry a cut-0E valve K, set close below the discharge-opening c. Thoughthis valve may be flat it is preferably curved in cross-section on the arc of a circle struck from a center in the axis of the spindle J. By rocking the spindle J this valve may be caused to open and close the discharge-opening c. As shown particularly in Fig. 3, I prefer to make the leading edge of the cut-off valve parallel to the edge of the discharge-opening, below which it first passes when executing the closing movement. This necessarily means that its leading edge is at an angle to the opposite edge of the opening. The movements of this spindle J are controlled from the scale-beam in the manner to be hereinafter described, and it will of course be understood that the closing of the valve is effected at such time as the proper quantity of material to balance a given weight placed on the weight-pan has been discharged into the receiving-box E.

It has been found in practice that it is impossible to cut off a large stream of flowing material in such a manner as to insure accuracy of weighing. It has been the practice, therefore, as described in my application, Serial No. 125,960, filed October 4, 1902, to employ a large stream and a small stream cut off successively by separate out off valves. I obtain in my present construction the same'effeet with practically one discharge opening and one cut-off valve.

It will be obvious, on reference to Fig. 3, that presuming the cut-off valve to start its closing movement at the edge of the discharge-opening, to which it is parallel, and to move sufficiently far to exactly close the opening, that at the midway point of its motion it has cutoff a greater percentage of the whole aperture than it will in moving from the midway position to the closed position. This means that the first movement in closing the aperture rapidly effects a considerable reduction in the size of the stream of material passing through the opening, after which a gradually tapering or lessening stream is allowed to flow during the latter part of the movement of the valve. I am enabled in this way to secure a large stream up to the point at which nearly the necessary quantity of material has been discharged and to finish the weighing with a small stream gradually tapering off to nothing. It is evident that the same effect might be obtained by employing other shapes than those shown for the front edge of the cut-off valve an d the sides of the opening. One variation is shown in the lowerpart of Fig. 4. In the upper part ofFig. 4 a substantially equivalent construction is shown. The cut-off opening is divided into two parts, 0 and 0, one being of considerably greater size than the other. While the cut-off valve is passingunderthe openingcany degree of movement of the valve produces a proportionate reduction the size of the opening. As soon, however, as the opening a is completely closed only a small stream is left flowing, and practically the same amount of movement of the scale-beam is required to shut off this small stream as was previously required to cut off the much larger aperture 0.

It will now be well to describe the method of operating the spindle J. On the end of this spindle outside the discharge-spout is secured an arm L, screw-threaded, as shown, so that a Weight 6 may be adjusted thereon. Through this arm 1 thread an adjustingscrew M, the point of which is adapted to engage the cross-bar f, formed on or secured to the scale-beam. A stopj serves to limit the fall of the arm L. When a given weight is placed onfithe weight-pan, the scale-beam tips and causes the crossbarf to tilt the arm L, thus rocking the spindle J and moving the cut-off valve from below the opening 0. Material may now flow freely through the discharge-spout into the receiving-box. As soon as enough has passed into the box to cause the scale-beam to tend to move to its balanced position the cross-barf moves from beneath the adjusting-screw M, permitting the weight e to rock the arm L and cause the cut-off valve to gradually close the opening 0 in the manner already described. It will be seen that the weight e exercises a downward pressure on the scale-beam, tending to make it Weigh light. This weight, however, is readily adjusted, so that it will compensate for the weight of the material between the discharge-opening and the receiving-box at the time the discharge-opening is closed and which of course falls into the box. By adjusting the screw M the exact position of the scale-beam when a complete cut-off occurs may be accurately regulated. By suitably using these two adjustments the scale may be easily adjusted to weigh accurately at any time and to operate on various materials of different specific gravity.

While the construction already described works with a suificient degree of accuracy for many purposes, yet for exceedingly fine weighing I find it necessary to use means whereby the greater part of the discharge aperture may be cut off while the amount of material discharged into the receiving-box is still, say half an ounce or an ounce, short of the full weight, so that the small stream may have a better opportunity to accurately supply the necessary amount to make the scale-beam balance. I therefore place on the weight-pan a weight short half an ounce or an ounce, as the case may be, of the full weight. Above the scale-pan I support a weight sufficient to make up the full amount. This weight, represented in Fig. 1 by the letter g, may rest on suitable supports, such as h, and in such a position that it will be lifted off these supports before the scale-beam has moved sufficiently to reach the balanced position. From this construction it follows that a large stream will flow freely until a sufficient amount has been discharged to lift the weight-pan or the weights thereon in contact with the weight g, when the larger part of the flow is cut off. Its further movement is temporarily checked until the small stream has made up the Weight required to balance the Weight g, when the cut-off occurs, as already described.

While this device operates best with a discharge-opening of the shape shown and described, yet it would operate with a considerable degree of success with a straight-sided opening. Care must of course be taken in any case to make the supports of such a height that when the weights or weight-pan have moved up into contact with the weight g that the cut-off valve shall have moved to the exact point desired to cut olf a larger part of the flow. Other constructions might of course be devised for increasing the Weight applied applied to the scale-beam at the proper time without departing from the spirit of my invention.

It will be noticed 011 reference to Fig. 3 that I employ a rotary agitator N, within the upper part of the discharge-spout. This may be of any ordinary construction, though I prefer to empoy one provided With blades 2', forming a spiral agitator. This agitator may by driven by a pulley, O.

\Vhat I claim as my invention is- 1. In automatic weighing apparatus provided with weigh-scales having a scale-beam and a delivery-spout having a substantially to close the said opening, the leading edge of the cut-0E valve being substantially parallel to the leading edge of the opening; an adj ustably-Weighted arm adapted to close the said valve; and an adjustable contact-point on said arm adapted to engage the scalebeam of the said weigh-scales, substantially as described.

Toronto, October 28, 1902.

WALTER NORTHROP.

In presence of- J. EDW. MAYBEE, A. J. OOLBOURNE. 

